Catalyst for the hydrogenation of nitro compounds



United States Patent 3,265,636 CATALYST FOR THE HYDROGENATIQN 0F NITRO COMPOUNDS Louis Spiegler, Woodbury, N.J., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Filed Mar. 26, 1963, Ser. No. 257,941 1 Claim. (Cl. 252-447) This invention is directed to improved hydrogenation catalysts and to their use in the catalytic reduction of nitro compounds.

Hydrogenation catalysts containing platinum or palladium supported on carbon are well known. Such catalysts have been prepared by impregnating various types of carbon supports with noble metal compounds. The carbon used tfor such supports has been mainly porous carbon of vegetable or animal origin. Due to the high porosity of such carbons, some of the noble metal becomes trapped within the pores and thus does not contribute to the activity of the catalyst. Another disadvantage is that such porous catalysts become fouled with the products of hydrogenation. In the reduction of :a nitro compound to the corresponding amine, several intermediate reduction products are formed which deposit on the catalyst and prevent further reduction from occurring in an efiicient manner. As a result, large amounts of tars are formed, yields are low and the quality of the final product is poor.

In order to overcome these disadvantages, it has been proposed to use non-porous oleophil-ic carbon blacks as supports for the noble metal. An increase in hydrogenation rates and improved yields of higher quality products have been noted with non-porous carbon supports tor the reduction of aromatic nitrobodies and polynitrotriamines as described in US. Patent No. 2,832,235.

It has now been discovered that, if a given quantity of a noble metal deposited on a nonporous carbon support and admixed with a porous carbon, the rate of hydrogenation using this catalyst is about twice that of a hydro genation process using the same amount of noble metal deposited on an all nonporous carbon support for various reductions such as: (1) reduction of nitrobodies to hydroxy amines in acid media, (Ex. 4), (2) reduction of aromatic chloro nitrobodies, without dechlorination, (3) reductive alkylation of aromatic nitrobodies with ketones, (4) reduction of aromatic nitrobodies, and (5) reduction of aromatic dinitro diphenyl ethers.

It is surprising and unexpected that the addition of a porous carbon, which in itself is not as satisfactory as nonporous carbon, would produce such a considerable advantageous effect on the rate of hydrogenation. This results in a substantial saving in the cost of the expensive noble metal and provides a more economical hydrogenation process.

An added advantage to the catalyst of the present vention is that technical grade nitro compounds which normally contain very minor amounts of poisons may be very advantageously reduced therewith to give higher yields of the corresponding amino compounds.

It is, therefore, an object of this invention to provide an improved hydrogenation catalyst. It is a further object to significantly and unexpectedly increase the rate of hydrogenation of nitro compounds to the corresponding amines, hydroxyamines, chloroamines and alkylated amines.

3,265,636 Patented August 9, 1966 "ice These and other objects will become apparent firom the following description and claim.

More specifically, the present invention is directed to a novel hydrogenation catalyst which comprises a nonporous canbon support having a surface area within the range of 20 to 150 sq. meters per gram, admixed with an activated, porous carbon support having a surf-ace area within the range of 200 to 1000 sq. meters per gram and platinum or palladium or a mixture thereof deposited on the total free surface of the combined supports at a loading within the range ot 0.05 to 1.0% by weight of the supports.

The present invention is also directed to a process for the hydrogenation oi nitro compounds to amines using the catalyst hereto-fore defined. This process is also directed to the hydrogenation of nitro compounds to hydroxy amines, chloroamines and N-alkyl amines.

The metals which may be deposited on the nonporous carbon which is later mixed with porous carbon to practice this invention are platinum, palladium or a combination thereof. The hydrogenation rate may be increased with prom-otors or activators. It is known that the presence of additional metals, metal oxides, or even non-metallic compounds improve the performance of a catalyst in a reaction of this type. The term activation is used to indicate that the catalyst has been improved in performance by having minor amounts of metals or metal oxides, hydroxides or carbonates combined with the metal catalyst. Activation results in improved hydrogenation rates and greater catalyst life.

In the present invention, activation is obtained by utilizing the oxides or hydroxides of iron, nickel, cobalt, magnesium, aluminum, manganese, chromium, vanadium or tungsten, all of which provide an activating influence. Combinations of activators may be used. Fluorides of boron or silicon may also be used as activators. Such activator may be added before, during or atter precipitation of the noble metal from solution as a hydroxide or carbonate.

The process of preparing the novel catalyst of this invention involves first suspending the nonporous, highly oleophilic carbon in copper-tree Water, as described in US. 2,823,235. An activator may be added at this point as a water-soluble solution of the activator metal salt; a solution of sodium carbonate or caustic is then added to precipitate the activator metal base carbonate or bydroxide. A solution of alkali metal bicarbonate or carbonate is added to the aqueous carbon slurry. A solution of the catalyst metal salt is added; the mass is heated to about C. and held at this temperature until a test portion, when filtered, shows no catalyst metal dissolved in the filtrate. This procedure assures that all the catalyst metal has been precipitated. The mass is then reduced by the addition of aqueous formaldehyde at 95 C. or by the use of hydrogen, hydrazine, alcohol, glycerine and the like. The catalyst paste obtained after reduction may be dried. When using hydrogen, the unreduced catalyst mass is filtered off and reduction is carried out just prior to using the filtered paste for the hydrogen reduction of nitro compounds, whereby the porous carbon is added into the reduction mass.

The concentration of the catalyst metal on the nonporous, oleophilic carbon support should be between about 1.0 and 10% by weight of the support.

The critical feature of this invention is the addition of a porous carbon to the non-porous carbon containing the metal catalyst. This addition consists of physical addition and mixing of a high surface, porous carbon with the catalyst paste as prepared above or with the dried catalyst. The porous carbon may be added to the reduction vessel together with the non-porous carbon-catalyst past composition. The reactor should be equipped with an agitator which thoroughly mixes the components. The mixing, both in the dry state and in situ in the reactor distributes the catalyst metal between the nonporous and the porous carbon, thereby forming the novel catalyst of the invention. The amount of porous carbon added to the oleophilic carbon catalyst is such as to produce a catalyst having a loading of about 0.05 to 1% of the catalyst metal based on the total weight of nonporous and porous support.

The use of low concentrations or loadings is desirable for the hydrogenation step, but the higher concentrations are preferred for ease of catalyst preparation. It is preferred to prepare the catalyst at high concentrations with subsequent dilutions to lower loadings for the hydrogenation. The amount of porous carbon added will depend on the loading of the catalyst metal desired. Preferably the amount of carbon added is such as to produce loadings from 0.05 to 1% of catalyst metal based on the weight of the total carbon. This concentration has been found to be the effective range. The use of porous carbon to form the initial concentrate results in loss of catalyst in the pores and it is therefore advantageous to use non-porous carbon for the concentrate. After dilution of the concentrate with porous carbon, the catalyst metal distributes itself throughout the total carbon wihout clogging up the pores of the porous carbon, thereby leaving available reactive catalyst sites.

The catalyst of the present invention is quite versatile. Not only does it reduce nitro hydrocarbons, nitrohalogenated compounds and nitro ethers to the corresponding amino compounds, but it also catalyzes the hydrogenation of nitro hydrocarbons to aminophenols in acid media and alkylates as well as reduces nitroamines with ketones.

The non-porous, oleophilic carbons upon which the catalyst metal is initially deposited have surface areas ranging from 20 to 150 square meters per gram.

Representative examples are listed in the following tables.

Table A EXAMPLES OF NON-POROUS CARBONS HAVING A SURFACE AREA OF 20 TO 150 Mfi/G.

Surface Trade Name Area, Type mfi/g.

Acetylene, Hiflo 60 Acetylene black, 50% compressed and less structure than ordinary acetylene black.

Acetylene, Standard 60 Acetylene black, approx. 100% Heavy. comf gressed, approx. 14 lbs./

Acetylene, Standard 60 Acetylene black, 50% com- Ordinary. pressed, approx. 6 lbs/cu. ft. Crofiex 77 80 Channel black (easy processing).

Kosmos M 94 Medium processing channel black (heavy compressed).

Kosmos T 105 Hard processing channel black (heavy compressed).

Dixie 5 140 Elglctrlical conductive channel ac r.

Sterling R 20 Semi-reinforcing furnace black (combustion).

Philblack A 29 High modulus furnace black (combustion).

Statex B 65 Fine particle furnace black (combustion).

P-33 23 Fine particle furnace black (thermal decomposition) Rubber Grade Velvet 25 Lampblack.

Lampblack (Type T).

Thermax; 19 Medium particle furnace black (thermal decomposition).

Spheron N o. 6 120 Mpagliulm processing channel ac r.

United 65 SPC 100 Super processing furnace black.

Monarch 81 120 Channel black.

Vulcan 3 69 Furnace black.

POROUS CARBONS The porous carbons which may be added to the nonporous carbon-catalyst composition have a surface area ranging from about 200 to 1000 square meters per gram.

Table B REPRESENTATIVE EXAMPLES OF CARBONS WITH SURFACE AREA GREATER. THAN 200 Mi /G.

Surface Trade Name Area Type mJ/g.

Darco G-6O 600 Activated Wood charcoal. Nuchar C-l000 1, 000 Do. Nuchar WA 600 Do. Nuchar B100 700 Do. Nuchar Cl15 700-950 Do. N uchar C-145 700-950 Do. Nuchar CEE. 700-950 Do. Nuchar C190 700-950 Do. Nuchar C 700-950 Do. Larnpblack Type T Acti- 208 Activated lampblack (treated vated. with air at 800 F.). Voltex 281 Conductive channel black. Carbolac-1 920 Channel black pigment, actlvated.

Carbolac2 850 Do. Carbolac-46 750 Do. Super Carbovar 400 Do.

ogul 340 Do. Mogul Spccial 330 Do.

ogul l 320 Do. Mogul A 300 D0. Monarch 71. 380 D0. Monarch 74 300 D0.

catalyst.

EXAMPLE 1 28 parts of Sh-awinigan Black compression) are stirred at room temperature with 700 parts of copper-free water containing 11.5 parts of sodium carbonate. The mixture is stirred and heated to 99 C. 3.5 parts of chloroplatinic acid (equal to 1.4 parts of platinum) dissolved in 75 parts of water are added dropwise over a period of 30 minutes, while holding the temperature at 99l00 C. The slurry is then held at this temperature for six (6) hours longer to assure complete precipitation of platinum values. The mixture is then cooled to 40, diluted with 300 parts of Water and the solid content of the resultant mixture is collected by filtration. The catalyst paste parts) represents a catalyst concentrate having a loading of 5% Pt based on the weight of the carbon black. For use in hydrogenation systems, it is mixed with a porous carbon black as described more fully in Examples IV to X below. This example may be repeated with a loading of 5% platinum on the support With Spheron No. 6, Dixie-5 and United 65 SPC, these carbon supports having a surface area of 120, 140 and 100 square meters per gram, respectively, to achieve essentially the same results.

EXAMPLE II 10 parts of sodium chloride are dissolved at room temperature in 50 parts of water. Agitation is started and 0.84 part of palladium chloride powder (=0.505 part of palladium) are added. The mixture is stirred for 2030 minutes at 29-30 C. until the palladium chloride is completely dissolved. This technique result-s in the formation of a chloropalladite solution. A solution of 0.14 part of chloroplatinic acid (equal to 0.056 part of Pt in 5.6 parts of water) is added. The mixture is stirred for 15 minutes and parts of water, 1.36 parts of ferric chloride hexahydrate [or one part of ferrous chloride (FeCl -4H O)], 5.6 parts of ShaWinig-an Black, and 30 parts of sodium bicarbonate are added. The mixture after stirring 3O minute-s at 26-27 C. is heated in 15 minutes to 95 Chi-1 C. and held at this temperature until a test portion of its liquors contains no dissolved precious metals. The reaction mass is then cooled to 5060 C. and the solid content of the resultant mixture is collected by filtration. The catalyst paste [24.9 parts (22.5% solids)] is washed on the filter with 60 parts of water and represents a catalyst concentrate having a loading of 9% Pd, 1% Pt, 5% Fe based on the weight of the carbon. This example may be varied by substituting the non-porous carbon blacks, Thermax MT, P-33 FT and Philblack A, said blacks having a surface area of support of 6.6, 18.1 and 29.0 meters per gram, respectively; the loading on these supports is 5% palladium, 0.5% platinum and 5% Fe The catalyst paste so obtained may be dried and mixed with a porous carbon to form a catalyst composition containing 0.05 to 0.1% of catalyst by weight of carbon support. Preferably the wet cata-lyst paste obtained as described in the above example is added as such to the reactor vessel with an amount of porous carbon necessary to give a catalyst concentration of 0.05 to 0.1% by weight of the total carbon in the system.

EXAMPLE III A dispersion of 5.6 parts of a carbon black (with a surface area less than 150 m. /g.) is prepared and 15 parts of sodium bicarbonate added. The mixture is stirred at room temperature for 30 minutes and then a solution of 0.467 part of PdCl (0.28 part Pd in 20 parts of 0 .55% HCl (dissolved at 95 C.)) and 2.72 parts of FeCl -6H O (or 2 part-s of ferrous chloride FeCl -4H O) in 50 parts of water are added. The mixture is heated to 95 C.; and either held one hour to precipitate the palladium as hydroxide; or 10 parts of 18.5% formaldehyde solution are added dropwise while stirring vigorously and held for /2 hour to precipitate the palladium as reduced metal.

In Examples 11 and III, the catalysts can be activated by using oxides or hydroxides of nickel, cobalt, magnesium, aluminum, manganese, chromium, vanadium or tungsten, instead of the oxides or hydroxides of iron as indicated. Combinations of the fluorides of boron and silicon may also be used as activators.

The reduction to colloidal noble metals can be done by the addition of aqueous formaldehyde, or by use of hydrogen or other reducing agents such as glucose, hydrazine, alcohol, glycerine and the like.

EXAMPLE IV nitrobenzene in concentrated sulfuric acid. Into the flask are placed 1000 g. of water, 66.2 g. of 96% sulfuric acid, 2 g. of Arquad T-50 (tallow trimethyl ammonium chloride), 2 g. of catalyst paste from Example I (which contains 0.02 g. Pt; 0.4 g. Shawinigan Black) and 1.97 g. of Carbolac-2. The catalyst loading amounts to 0.84% Pt by weight of total carbon.

The reactor is flushed with hydrogen and heated to 90 C. A mixture of 94 g. of nitrobenzene and 38.7 g. of 96% sulfuric acid is added to the flask at a rate of 1.6 to 1.8 ml./min. while at the same time adding hydrogen at such a rate that the pressure in the flask remains essentially constant. The temperature is maintained by external cooling at 9293 C. and the total pressure at 760 mm, the partial pressure of hydrogen being about 200 mm. The sulfuric acid added with the nitrobenzene is equivalent to the basic reduction products formed, so that addition of the mixture to the flask produces no change in the overall acidity.

Hydrogen is absorbed at a rate of 1.5 cu. ft. per hour. The nitrobenzene is added in 60 minutes. The solution then contains 66.7 g. of p-aminophenol and 12.8 g. of aniline, equivalent to yields of 80.0% and 18.0%, respectively.

By following the details of Example IV using a catalyst containing 0.42% Pt. by weight of carbon support, hydrogen is absorbed at the rate of 1.5 cu. ft. per hour giving a yield of 77.6% of p-aminophenol.

A catalyst prepared according to the method described in U.S. 2,285,277, containing less than 1% Pt. by weight of porous carbon support is inactive in the process of Example IV, if the surface area exceeds 600 m. g. (see Table V1 for results with 1% Pt. on Daroo-G60).

Catalysts containing 1% Pt. (formaldehyde reduced) prepared according to U.S. 2,285,277 by direct deposition of the catalyst metal onto a non-porous carbon black having a surface area less than 150 m. g. are less active than the catalysts of the invention prepared by the distribution or addition of porous carbon to non-porous catalyst support (see Table V II).

Similarly, a catalyst prepared according to U.S. 2,823,235 by dilution of non-porous carbon support with additional non-porous, low surface area carbon is less active than the catalyst of the invention (see Tables II and IV).

The following Table I lists the results obtained with various porous caribons added to a catalyst paste, prepared as in Example I, in the hydrogenation of nitrobenzene to produce p-aminophenol.

Table IA shows the activities produced with the carbon surface area extended to 1700 mF/liter of reaction solution, using 0.02 g. Pt. in hydrogenations of nitrobenzene at C. i

Table IB shows the results obtained at 0.5% Pt. loading (0.015 g. Pt.) using a fixed amount of various porous carbons in hydrogenations at C.

By following the procedure of Example IV, the following nitro compounds are hydrogenated to p-hydroxyamines:

o-Nitrotoluene to 4-amino-3-methylphenol 1-nitronaphthalene to 4-aminonaphthol o-Chloronitrobenzene to 4-amino-3-chloropl1en0l m-Chloronitrobenzene to 4-amino-2-chlorophenol 2-nitrobiphenyl to 2-amino-5-hydroxybiphenyl EXAMPLE V A nickel-clad autoclave, jacketed for heating or cooling with circulating water and equipped with baflles and eflicient agitation, is charged with: 2000 parts of 3,4-dichloro-l-nitrobenzene; parts of water; 20 parts of morpholine; 3 parts of catalyst paste of Example I (equal to 0.03 part of platinum as hydroxide and 0.6 part of Shawinigan Black) and 3 parts of Carbolac-2.

The quantity of morpholine employed corresponds to 1% of the weight of nitrobody; that of the catalyst to 1 part platinum to 66,000 parts of nitrobody. (Note: 1 part Pt. to 200,000 parts nitro is also effective.)

Air in the autoclave and lines is then displaced by pressurizing with nitrogen and releasing the pressure through the vent system. The autoclave is then pressurized to 500 p.s.i.g. and allowed to stand without agitation for 20 minutes to assure a gas tight system. The nitrogen is then displaced with hydrogen by successive pressurizing to 100 p.s.i.g. and venting to zero p.s.i.g. The temperature of the circulating water in the jacket is adjusted to 60 C.; the agitator started; and the hydrogen pressure is increased to 200 p.s.i.g. The charge absorbs hydrogen rapidly with the evolution of heat. The temperature of the charge rises to 75 C., with the cooling bath temperature held constant at 60 C. The autoclave is rep-ressurized to 200 p.s.i.g. after each 100 lb. drop in pressure. After 100 to 109 minutes no further 7 rapid hydrogen absorption is noted. The charge is then heated to 95 C., and held at 500 p.s.i.g. for 30 minutes longer to assure complete reduction.

Table I '8 no appreciable increase in the mole percent dechlorination, and with a decrease in the percent of HCl insolu'bles.

DILUTION OF 5% Pt ON SHAWINIGAN BLACK WITH VARIOUS PO ROUS CARBON SUBSTRATES (A) Using 2 g. catalyst (24 paste of Example I, 5% Pt on Shawinigan Black (dry basis) containing 0.02 g. Pt: 0.4 g. Shawinigan Black m1 surface area). Total surface area extended to 1700 ml with substrates listed below.

[Reduction temperature 85 0.; 600 r.p.m. agitator speed] Substrate Reduction Rate p-Aminophenol Weight g. Final H absorp., Ml. Feed, Min/Mole Percent Name Mfi/g. Added lgfierLcen cu. ft./hr. per Min. Nitrobenzene Yield Lb./hr./gal.

Daroo G-60 600 2. 8 0.63 1.70 2. 16 61.0 75. 5 0. 71 Nuchar 1 C1000 1, 000 1. 7 0. 95 1. 40 1. 67 80. 0 81. 0 0. 58 Mogul Special- 330 5. 1 0. 37 2. 2. 50 53. 0 73. 8 0. 79 Mogul A 300 5. 6 0.33 2. 2. 70 50. 0 76. 6 0.88 Carbolac-l 920 1. 82 0. 90 2. 2. 70 5O 76. 0 0. 87 Oarbolac-2 850 1. 97 0. 84 2. 33 2. 70 49 71. 5 0.81 Voltex 280 6. 0 0.31 1. 54 2. 00 67 81. 0 0. 69

(B) Using 1.5 g. catalyst paste, Example I, 5% Pt on Shawinigan Black containing 0.015 g. Pt; 0.3 g. Sliawinigan Black (18 In. surface area). Extended to 0.5% Pt loading with substrates (2.7 g.) listed below.

[Reduction temperature 90 0.; 600 r.p.m. agitator speed} Substrate Reduction Rate p-Aminophenol Name M /g. Total Surf. H2 absorp., Ml. Feed, Min/Mole Percent Lb./hr./gal.

Area, m? cu. ft./hr. per. Min. N itrobenzene Yield Super Carbovaron 400 1, 088 2. 10 2. 4 57 63. 4 0.63 Carbolac 46. 750 2, 043 1.65 2.0 67 79. 4 0. 68 Monarch 71 380 1, 048 2. 2. 8 48 72. 5 0. 88

1 Platinum deposited on Nuchar by method of U.S. Patent No. 2,285,527 7 was inactive.

The hot reduction mass is then filtered, the filtrate allowed to settle at 80 to 85 C., and the layers separated. The Water layer (470 parts) has a pH of 8.4

and contains 0.42 g. chloride ion per 100 parts, which 40 represents a 0.5 mole percent dechlorination.

The dichloroaniline layer is dehydrated by heating at 100i10 at 20 mm. of Hg to yield a 98.9% pure product, 3,4-dichloroaniline, having a freezing point of 71.1

With the Shawinigan Black dilution (1), the hydrogen pressure starting at 200 p.s.i.g. and 60 C. temperature had to be increased in the first 30-45 mins. to 500 p.s.i.g. and 90 C. to maintain the rate of hydrogen absorption, and it required (4) four hrs. to effect complete reduction. With the Carbolac-Z dilution, the absorption occurred rapidly at 200 p.s.i.g. pressure, and only a temp. in-

crease was needed to effect completion in 1.8 hours.

Table II 3,4DICHLOROANILINE BATCH HYDRO GENATIONSPt, MORPHOLINE (2000 PART 3,4-DI- CHLORO-l-NITROBENZENE)EFFECT OF DILUTIONS AND CARBOLAC-2 WITH SHAWINI GAN BLACK Finished Isolated 3,4-dichloroaniline Reduction Reduction Part Dilution Percent Pt I ime Pt with- Loading Minutes Mole Percent Percent F.P. Percent pH Percent Purity HCl 0. N02 b Dechlor. insol.

0.03 Shaw. B1ack 0.83 249 8. 7 0. 45 98.3 0.52 70. 6 0. 01 0.03---" Carbolac2 0.83 109 8. 4 0. 54 98. 9 0.28 71.2 0. 03 0.02 do 0. 59 180 8. 2 0.71 98. 7 0.96 70. 5 0. 03 0.02 do 0. 59 180 8. 2 0. 71 98. 7 0. 96 70.5 0. 03

B By VPO Analysis. b By TiCl Titration.

Substitution in Example V of three parts of low surface area mF/g.) Shawiniga'n Black for the three parts of Canbolac-Z (850 m. g.) gives a much slower reduction cycle.

Table II summarizes the results obtained using 0.03 and 0.02 part of platinum per 2000 parts of 3,4-dichloronitrobenzene and 20 parts of morpholine using 5% Pt on Shawinigan Black diluted with (1) Shawinigan Black to 0.83% Pt loading and with (2), and (3) Carbolac-2 to 0.83 and 0.59% Pt.

The extension of concentrated catalyst with Carbolac- 2 results in a 2.3 fold increase in the reduction rate with 4-chloro-3-nitroluene 2-ch1oro-4-nitroluene 2,5-dichloro-l-nitrobenzene o-, and p-Chloronitrobenzenes 1-br0mo-4-nitrobenzene l-fluoro-4-nitrobenzene 9 2chloro-4-nitroaniline 4-chloro-2-nitroanisole 2-chloro-4-nitrobenzoic acid 6-chloro-2-nitrobenzoic acid, Na salt and 4 chloro-3-nitrobenzene sodium sulfonate.

EXAMPLE VI A steel or nickel-clad pressure reactor, which is jacketed for heating or cooling with water, and which is equipped with baflies and an eflioient agitator which rotates at 450 r.p.m. is used for the hydrogen reduction. The reactor is charged to about 20-25% of its capacity with 700 parts of 3,4-d-ichlo'roaniline at 7585 C., 140 parts of water, 10 parts of morpholine, parts of catalyst paste of Example I (equal to 0.05 part of platinum as hydroxide and 1 part of Shawinigan Black) and 15.7 parts of Carbolac-2. The autoclave is then pressurized with hydrogen to 140 p.s.i.g. and the agitator is started. Ilhe temperature of the circulating bath is adjusted to 93:2 C. Molten 3,4-dichloro-1-nitrobenzene is then injected under pressure in portions of approximately 59 parts each As the nitrobody is reduced, a drop in pressure is observed due to consumption of the hydrogen. An external reservoir limits this pressure drop to about p.s.i. This pressure drop is also accompanied by a rise in temperature. The temperature is controlled between 90-1 10 during the reaction by circulating the water at 90:5" C. through the jacket. After each portion of nitrobody is reduced, the system is repressurized with hydrogen to 140 p.s.i.g. prior to adding another portion of nitrobody. In this manner, each portion of nitrobody is completely hydrogenated before adding the next portion. The time required to reduce each portion of nitrobody is observed and the rate of reduction at 135 p.s.i.g. (average)--parts of 3,4- dichloro l-nitrobenzene reduced per minute per part of platinum is calculated (g. nitro/min/g. P-t)e.g., by dividing the weight of nitrobody by the product of time required for its hydrogenation by the weight of platinum used.

The above hydrogenation process can be operated continuously by removing portions intermittently and recycling the catalyst, or it can be run semi-continuously by feeding nitrobody until the autoclave is filled to 65- 75% capacity.

3,4-dichloroaniline is isolated as described in Example V. 6

Rates of reduction obtained with additions of Carbolac- 2 to platinum loadings from 0.3 to 0.8% using 0.05 part of Pt/ 2000 parts of nitrobody are compared in Table III with 5% Pt on Shawinigan Black undiluted. The rate increases With increase in Carbolac-Z added.

Table III EFFECT OF ADDITION OF CARBOLAC-2 Reduction Rate Parts Carbolac-2 Percent Pt Loading Added EXAMPLE VII 10 Table IV DILUIION OF 5% Pt ON SHAWINIGAN BLACK (EXAMPLE I), 0.3% Pt LOADING; 0.03 G.

Reduction Rate 3,4-dichloroaniline Diluting Carbon Part nitr0/min./ part Pt Mole Percent Dechlor.

F.P. C.

Carbolac-2 Mogul A Shawinigan Black c n-00 NIOQO EXAMPLE VIII dry basis), 0.32 g. of Carbolac-Z, 3.4 ml. of Water and 0.1 ml. of 85% phosphoric acid are charged into the bomb and the equipment is tested at 600-700 p.s.i.g. with nitrogen. The nitrogen pressure is then vented and replaced with hydrogen by repeated pressurizing at 300 p.s.i.g. followed by venting to zero p.s.i.g. 500 p.s.i.g. hydrogen pressure is then applied to system While heating to 100 C. The hydrogenation is controlled manually at 400-500 p.s.i.g. H pressure. The initial hydrogen absorption is rapid, and there are 15-17 100 lb. drops in pressure in about 1012 min. This is accompanied by a rapid rise in temperature from 100-150 C. When this initial temperature kick subsides, heat is applied to maintain the temperature at l75i3 C., while holding the hydrogen pressure at 400-500 p.s.i.g. until no further absorption occurs. The total time for hydrogenation is four hours.

The bomb is cooled to 30:5 C., opened and the liquid two-layer system removed by decantation. The charge is filtered to separate catalyst; the water layer (33.5 g.) separated; and the methylethyl ketone solution of the alkylated di-amine is concentrated by distillation to 130i5 C. at 10 mm. Hg to recover the excess methylethyl ketone. The crude concentrate 93.0 g. (calc. yield: 94 g., M.W. 220) is finally vacuum distilled at 115 i5 C./1i0.2 mm. Hg to obtain pure N,N-di(sec. buty1)-pphenylenediamine.

The results obtained when 1% Pt on Darco G- (prepared as described by Henke et al., in U.S. 2,285,277) is substituted for the catalyst in Example VIII are not as satisfactory. (See Table VIII.) The Darco supported catalyst is less active and does not filter as readily.

The use of 1% Pt on only non-porous Shawinigan Black as support, resulted in the exclusive formation of p-phenylenediamine. None of the desired alkylated product was formed.

Ketones having the formula RCOR . wherein R and R have 1 to 4 carbon atoms and are alike Part nitrolminlpart Pt or difierent may be utilized in the place of methylethyl ketone of this example. p-Nitroaniline remains as the other reactant.

, EMMPLE IX The procedure described in Example VI is also used for the continuous hydrogenation of orthonitrotoluene to produce orthotoluidine.

In this process, orthonitrotoluene is injected in portions of 58 parts each'under pressure 140 p.s.i.g. H to an agitated slurry at 450 r.p.m. of 750 parts of orthotoluidine, 250 parts of water, 3 parts of catalyst paste containing 4.5% Pd; 0.5% Pt; 5% Fe as hydroxides on Shawinigan Black (equivalent to 0.03 g. Pd-Pt; 0.6 g. Shawinigan Black) and 9 g. of Carb oIac-Z at :10" C.

The rate of reduction under these conditions is 800 g. orthonitrotoluene/min./ g. Pd-Pt.

Comparative rates obtained from various additions of porous carbons to a catalyst paste containing 4.5% Pd;

0.5% Pt; Fe on Shawinigan Black are Table V.

Table V shown in 12 rate of hydrogenation of nitro compounds to amines, hydroxy amines, chloroamines and alkylated amines. This several fold unexpected increase results in a direct saving in the amount of expensive platinum and/or palladium EFFECT OF ADDITION OF CARBOLAC-2 ON ORTHONITROTOLUENE REDUCTION (0.03 G. Pd-Pt) Other nitro compounds which may be hydrogenated to the corresponding amines by the method described in the above examples are the following:

m-Dinitrobenzene 2,4-dinitrotoluene 2,6-dinitrotoluene Nitrobenzene 2-nitropropane Nitrocyclohexane 2,4,6-trinitrotoluene Beta-nitronaphthalene p-nitroanisole EXAMPLE X The mixture, after displacing the air in the system 45 with hydrogen as described in Example V, is hydrogenated at 100-130 C. at 300-500 p.s.i. hydrogen pressure. The hydrogenated product is filtered from the catalyst, and

the clarified filtrate is cooled to obtain crystals of pure 5 white 4,4'-diaminodiphenylether.

The addition of Carbolac2 to 5% Pt on Shawinigan Black results in a several fold acceleration in rate, While using one-half the quantity of platinum, e.g. 1 troy oz.

metal necessary to reduce the same amount of nitro compound with known catalysts.

Other dinitrodiph'enyl ethers which may be reduced in the practice of this invention include: 2,4-dinitro-4- methyldiphenyl ether, 3,4-dinitrodiphenyl ether, 2,2-dinitrodiphenyl ether, 2,3'-dinitrodiphenyl ether, 2,4'-dinitro-3-methyl-S-methoxydiphenyl ether and 4,4'-dinitro- Z-ethyldiphenyl ether.

The following data set forth comparative performances of the catalysts of the prior art which performances substantiate the unexpected significance of the heretofore described novel catalysts of the present invention. The tables referred to are those tables preceding this data. RESULTS FROM DIRECT PREPARATION OF 1% Pt LOAD- INGS ON HIGH SURFACE AREA CARBONS Catalysts containing 1% Pt (formaldehyde reduced) prepared directly by the procedure described in US. 2,285,277 on high surface area supports (type B carbons) such as Darco G-60, Nuchar C-l000 and Carbolac-2 are less active than the concentrated catalyst of Example I diluted with the type B carbons.

1% Pt (CH O reduced) on Carbolac2 (850 m. /g.) or on Nuchar C1000 (1000 m. /g.) is totally inactive, as previously indicated. Results from 1% Pt on Darco G- (600 m. /g.) are shown in Table VI. This cata- 0 lyst is considerably slower, e.g. less active, then diluted catalysts prepared by -re-distribution of noble metal values from a low surface area support to a larger surface area as described in Example IV (compare Table I with Table VI).

Table VI DARCO G-60 SUPPORT (SURFACE AREA M. /G.=600) Catalyst prepared from ehloroplatinic acid, alkali, and formalin as described in U.S. 2,285,277.

' Catalyst Reduction Rate -Amino henol Agitator Red. p p

Speed, Temp.,

R.p.m C. G. Pt G. 0 Percent Pt Hg Absorp. Ml. Feed/ Min/Mole Percent LbJhrJgal.

Load. Cu. ft./hr. Min. Nitrobenzene Yield the noble metal produce a considerable increase 'in the 70 RESULTS FROM DIRECT PREPARATION OF 1% Pt LOAD- INGS ON LOW SURFACE AREA CARBON BLACKS 1% Pt (reduced metal form) prepared directly onto carbon blacks (US. 2,285,277) with surface areas less 75 than m. /g. (type A carbon blacks) are less active than the catalysts obtained by the distribution (or dilupalladium, and mixtures thereof being deposited on the tion) technique. Results are shown in Table VII (comtotal free surface of said admixed supports at a loading pare with Table I). within the range of 0.05 to 1.0% by weight of said sup- T able VII 1% Pt (REDUCED METAL FORM) ON TYPlialrgARBoN SUPPORTS (SURFACE AREA 60-120 [Reduction temperature 85 C., agitator speed 800 r.p.m.]

Reduction Rate p-Aminophenol Carbon Support I H; Absorp. M1. Feed/ Min/Mole Percent Lb./hr./gal.

cu. ftJhr. Min. Nitrobenzene Yield Shawinigan Black (60 111. 2.) 0.65 0.77 172 71. 0.19 Spheron No. 6 (120 mg.) 1.00 1. 14 117 71. 0.29

Table VIII shows the results obtained with 1% Pt. on ports, the relative proportions of said carbons being in the Darco G-60 (prepared as described in US. 2,285,277) range of about 4:1 to 1 of porous carbon to non-pocompared with those of Example VIII. rous carbon, said noble metal being initially deposited on Table VIII REDUCTIVE ALKYLATION OF p-NITROANILINE WITH METHYL ETHYL KETONE 0.004 G Pit/59 G. PNA) Catalyst Support Crude Concentrate VPC Analysis Hours Minutes Weight Percent Reduction Filtration Yield g. PPD

Time Time Dialkyl Equiv. Percent Name G. PPD Percent Purity PPD Dialkyl PPD llgarco 5G-60 38 6. 60 91. 2 0.9 0.00 98.1

1X10- Carbolwz 32 4. o 24 93.0 0.1 o. 04 99.8

PPD =p-Phcnylenediamine. B Percent PPD Equivalent: By Indo-phenoI formation. Blue color formation with phenol and caustic soda.

It is thus clear that the herein described and claimed said nonporous carbon prior to being admixed with said invention represents a novel and unexpected contribution activated porous carbon support. to the art.

The preceding representative examples may be varied R f r Cit d by th E a i r within the scope of the present total specification dis-- closure, as understood and practiced by one skilled in the UNITED STATES PATENTS art, to achieve essentially the same results. 2,716,13 5 8/1955v Winstrom 260 580 As many apparently widely different embodiments of 2 768 209 10/1956 Kuhn 26O 5y80 this invention may be made without departing from the spirit and scope thereof, it is to be understood that this 2,797,244 6/1957 Ginsley 26'0" 580 invention is not limited to the specific embodiments there- 2,911,375 11/1959 Coley et al. 252-466 of except s defined in the pp e claim- 2,914,488 11/1959 Gilb rt 252 466 The embodiments of the invention in which an ex- 3,073,865 1/1963 spiegler 252 N7 ga f Pmflege flamed are defined as 5 3,127,356 3/1964 Hamilton et al. 252-447 X A hydrogenation catalyst consisting essentially of a non-porous carbon support having a surface area within the range of 20 to 150 square meters per gram, said nonporous carbon support being admixed with an activated CHARLES R PARKER MAURICE A. BRINDISL porous carbon support having a surface area within the range of 200 to 1000 square meters per gram, a noble D, R, MAI-IANAND, R, D, EDMONDS, H, S, MILLER, metal selected from the group consisting of platinum, WEISSMAN, Assistant Examiners OSCAR R. VERTIZ, Primary Examiner.

Examiners. 

